Prepare a double boiler or fit a heatproof bowl over a small saucepan of simmering water. In the bowl, combine the egg yolks and 1/2 cup of sugar, and whisk until frothy. Transfer the bowl immediately to an ice bath, stirring occasionally, until cool.
Meanwhile, in a separate bowl, whip the heavy cream to medium peaks. Fold the whipped cream into the cooled egg yolk mixture and then stir in the cinnamon.
In a separate mixing bowl, whip the egg whites and amaretto liqueur until soft peaks form and fold that into the egg yolk-cream mixture. Pour the mixture into a loaf pan or small baking dish and freeze the mixture until soft-frozen, about 4 hours.
While the semifreddo freezes, toss berries with the lemon juice and remaining 1/4 cup of sugar in a small bowl. Lightly mash with a fork to crush some of the berries. To serve, spoon the semifreddo into individual dessert dishes, top with some of the berry mixture and garnish with shaved chocolate.
Recipe courtesy of Michael Chiarello